Partial composite action

Background

There is a global trend towards more and heavier vehicles on the roads, which implies that the existing bridges are exposed to higher and more frequent loads than they, in many cases, originally were designed for. If a bridge don’t have a sufficient load capacity, it has to be either strengthened or replaced.
Replacing a bridge is an action that consumes a lot of natural resources and money. A lot of research is conducted in order to develop more environmental friendly alternatives to cement, carbon capture and storage techniques and cost-efficient ways of using hydrogen to decarbonising the steel production. However, even if the emissions from the material production is cut down a lot, the best bridge replacement (in terms of CO2 emissions) will still be the one that can be avoided by an effective bridge assessment and appropriate strengthening techniques.

Therefore, the focus should be on keeping the existing structures in service and to avoid building new bridges, if possible. This project aims to study a strengthening method that has the potential to reduce the time-, cost- and material spent on strengthening of existing non-composite steel girder bridges.

Aim & Objectives

The overall aim of the project and the studied strengthening concept is to simplify and optimize future strengthening measures of existing steel girder bridges with non-composite concrete deck slabs, in order to minimize costs, traffic disturbance and environmental impact. This can be achieved by tailoring the degree of composite action required between the steel girder and the concrete deck slab, to obtain the required extra bending moment capacity. Optimizing the number, location and type of shear connectors can enable a cost- and time-efficient strengthening method, with a very low material consumption and thus also very low CO2 emissions.
The main objective is to create design-, execution- and installation recommendations, which will be compiled in a “Design guide” that will be published in the end of the project.

Facts

Financers: BBT/Trafikverket and SBUF
Lead partner: LTU
Partners: Chalmers
Start date: 2023-07-01
End date: 2025-12-31
Total budget: 4 MSEK
Team Members: Peter Collin, Robert Hällmark och Victor Vestman